FEMORAL INJECTION OF ECHO CONTRAST-MEDIUM MAY INCREASE THE SENSITIVITY OF TESTING FOR A PATENT FORAMEN OVALE

Objective: The diagnosis of a patent foramen ovale (PFO) as a cause of stroke is of increasing interest especially in young (<45 years) pati ents. Methods: We studied potential right-to-left shunting using trans esophageal echocardiography (TEE) and bilateral transcranial Doppler s onography (TCD) of the middle cerebral artery (MCA) simultaneously in 44 patients. All patients were younger than age 45 years and suffered from an acute ischemic stroke or transient ischemic attack. Other poss ible etiologies were excluded. Echo contrast medium was injected in an alternating mode via antecubital or femoral veins. Tests were perform ed with and without the Valsalva maneuver. The criteria for a PFO were that the contrast pass from the right to the left atrium (TEE) and ea rly detection (<10 seconds) of more than 10 micro air bubbles in at le ast one MCA by TCD. Results: A PFO was diagnosed in 22 patients (50%). The detection rate with TEE/TCD was 11.4%/4.5% via antecubital inject ion, 18%/13.6% via antecubital injection plus the Valsalva maneuver, 8 8.60/0/36% via femoral injection alone, and 50%/50% via femoral inject ion plus the Valsalva maneuver. The difference between femoral and ant ecubital injections was significant with and without the Valsalva mane uver (p < 0.01, chi(2) test). There were no differences between TEE an d TCD after femoral injection with the Valsalva maneuver. The brain tr ansit time was 4.6 +/- 2.1 seconds for femoral injection and 6.3 +/- 4 .1 seconds for antecubital injection. Conclusions: The sensitivity in detecting a PFO was markedly increased by femoral injection. This may be caused by different inflow patterns to the right atrium: inferior v ena caval now is directed to the right atrial septum, whereas superior vena caval flow is directed to the tricuspid valve. Thus, femoral inj ection may help to improve the detection of PFO and may explain the di fferences between TEE and TCD findings in previous studies.